Research


The coming years will be an exhilarating time in astronomy. New telescopes with high sensitivity (e.g., GMT, TMT, JWST, SKA) and wide field of view (e.g., LSST, WFIRST) will be built and operate soon. These observatories will deliver unprecedented details of light from stars and gas in, around, and outside of galaxies. For theorists, providing a physical understanding of such detailed observations will be a challenging endeavor.

My research interests have centered on physics of interstellar medium (ISM) and star formation (SF). The most fundamental questions of this research field would be how do stars form? and what shapes the ISM? These are tightly connected questions because stars are born in the ISM that maintains turbulence and multiple thermal phases by gaining energy and momentum from stellar feedback. However, due to the lack of computing power and efficient numerical methods, it has been a common practice to model one process in detail, while the other is held fixed. This approach disconnects the connected system and limits the predictive power of such models. The primary accomplishment I have achieved recently is the development of a numerical framework (called TIGRESS) that models the star-forming ISM with self-consistent treatments of star formation, stellar feedback, and ISM physics. The TIGRESS simulation facilitates quantitative predictions to essential properties of the star-forming ISM, such as turbulence characteristics, thermal phase balance, star formation rates, and multiphase outflow properties.

Similarly, a fundamental question in the field of galaxy formation, how do galaxies form and evolve? cannot be answered without a deep understanding of larger and smaller scale physics. Large-scale structure of dark matter guides baryonic matter to assemble, and small-scale energetic feedback from massive young stars and black holes shapes galaxies that we see. Significant progress has been made by running cosmological N-body simulations from well-defined initial conditions informed by the standard LambdaCDM cosmology, establishing the hierarchical structure formation paradigm. The overarching research theme in this field now is to make progress toward the non-linear regime where small-scale baryonic physics plays a crucial role. Because of limited computational resources, baryonic processes are often included as subgrid models by adopting or tuning prescriptions to match specific empirical relationships. Again, the predictive power of such models is significantly limited.

The overarching goal of my current research is to improve our understanding of ISM/SF physics and propagate it to galaxy formation theory, and vice versa. The TIGRESS simulation suite I recently developed positions me ideally for developing new physics-based subgrid models for small-scale ISM/SF/feedback processes. The successful development of new subgrid models will make immediate progress on new galaxy formation theory with full prediction power. I will pursue further improvements to the current simulation suite by employing additional capabilities of the new Athena++ code, including mesh-refinement feature and molecular chemistry, radiation, and cosmic ray modules. Synthetic observations constructed from new simulations will be used to test numerical simulations and unveil underlying physics of complex observations. Completion of all objectives listed above will bring comprehensive knowledge about fully nonlinear, multi-scale, multi-physics phenomena of the Universe within reach.


Publications


ORCID ADS

  1. Three-phase Interstellar medium in Galaxies Resolving Evolution with Star formation and Supernova feedback (TIGRESS): Algorithms, Fiducial model, and Convergence
    Kim, Chang-Goo & Ostriker, Eve C.
    2017, ApJ, 846, 133
  2. Recovering interstellar clouds with HI spectral lines: A comparison between synthetic observations and 21-SPONGE
    Murray, Claire E., Stanimirovic, Snezana, Kim, Chang-Goo et al.
    2017, ApJ, 837, 55
  3. Superbubbles in the Multiphase ISM and the Loading of Galactic Winds
    Kim, Chang-Goo, Ostriker, Eve C., & Raileanu, Roberta
    2017, ApJ, 834, 25
  4. Chemistry and radiative shielding in star forming galactic disks
    Safranek-Shrader, Chalence, Krumholz, Mark R., Kim, Chang-Goo et al.
    2017, MNRAS, 465, 885
  5. Vertical Equilibrium, Energetics, and Star Formation Rates in Magnetized Galactic Disks Regulated by Momentum Feedback from Supernovae
    Kim, Chang-Goo & Ostriker, Eve C.
    2015, ApJ, 815, 67
  6. Momentum Injection by Supernovae in the Interstellar Medium
    Kim, Chang-Goo & Ostriker, Eve C.
    2015, ApJ, 802, 99
  7. Three Dimensional Hydrodynamic Simulations of Multiphase Galactic Disks with Star Formation Feedback: II. Synthetic HI 21 cm Line Observations
    Kim, Chang-Goo, Ostriker, Eve C., & Kim, Woong-Tae
    2014, ApJ, 786, 64
  8. Long-Term Evolution of Decaying Magnetohydrodynamic Turbulence in the Multiphase Interstellar Medium
    Kim, Chang-Goo & Basu, Shantanu
    2013, ApJ, 778, 88
  9. Three Dimensional Hydrodynamic Simulations of Multiphase Galactic Disks with Star Formation Feedback: I. Regulation of Star Formation Rates
    Kim, Chang-Goo, Ostriker, Eve C., & Kim, Woong-Tae
    2013, ApJ, 776, 1
  10. Regulation of Star Formation Rates in Multiphase Galactic Disks: Numerical Tests of the Thermal/Dynamical Equilibrium Model
    Kim, Chang-Goo, Kim, Woong-Tae, & Ostriker, Eve C.
    2011, ApJ, 743, 25
  11. Galactic Spiral Shocks with Thermal Instability in Vertically Stratified Galactic Disks
    Kim, Chang-Goo, Kim, Woong-Tae, & Ostriker, Eve C.
    2010, ApJ, 720, 1454
  12. Galactic Spiral Shocks with Thermal Instability
    Kim, Chang-Goo, Kim, Woong-Tae, & Ostriker, Eve C.
    2008, ApJ, 681, 1148
  13. Interstellar Turbulence Driving by Galactic Spiral Shocks
    Kim, Chang-Goo, Kim, Woong-Tae, & Ostriker, Eve C.
    2006, ApJ, 649, L13

Movie


TIGRESS: Three-phase ISM in Galaxies Resolving Evolution with Star formation and Supernova Feedback

Kim & Ostriker, 2017, ApJ, 846, 133


Superbubble driven by multiple SNe

Kim, Ostriker, & Raileanu 2017, ApJ, 834, 25


Core in MB10

Kim & Ostriker 2015b, ApJ, 815, 67


Supernova Remant in the Two-phase ISM

Kim & Ostriker 2015a, ApJ, 802, 99